I would say the whole treating it with melafix in a rubbermaid bin with uncycled water probably stressed the hell out of an already stressed fish. Not to mention the move to the bin, and then back to the tank. Honestly, I'm surprised its still alive.
Had you just removed his tank mates, bumped up his temp, and added a bit of salt like was suggested in your first thread, he'd probably be on his way to recovery by now.